Regulator control equipment



March 16, 1943. J CARUN A 2,313,921

VREGULATOR'GONTROL EQUIPMENT Filed: Jan. 9, 1942 12 Line I m Lzne Fr 2. a

H .7 souq I k 0 5 'Ll ne a e2 E, o. 7. Lme mm IN VENTORS D: WITNESSES" Herbert J. Carlin and b Leslze N. Crzchton, decegs d, by

Ruth M. Crzchton, Admmzslratm.

0.4 g 70 "W as we POWE FACTOR an rhesus Nllh. 1.6 fists REGULATOR l1 Application January ii, 19412, Non excess invention relates regulator systems id ulcularly to apparatus for regulating thr voltgo of alternating current circuits.

In regulating systems, particularly in. rural districts having low capacity feeders, where tapchanging voltage regulators are employed to r 'ntciu normal voltage during the heavy load periods, frequent operation of the contact-maktrig toys of the regulator produces excessive conto t wear. Time delay is therefore, usually pro- :L in the tep-changer control circuit.

The time delay introduced in the control circult of the tepchanging transformer type of regulator makes it essential that e. definite time st elapse before the regulator is actuated. In oroctice such definite time delay, usually between ill seconds and, 1 minute, necessitates extra. equipment and expense while reducing the .fectiveness of the regulator for whether the voltage change encountered is a gradual change in small increments or a sudden change in large increments, the time delay is the same.

A. voltmeter relay of the induction type and often used in protective relay circuits, has an in verse time delay characteristic because of the presence of a. permanent magnet therein. The use of such a voltmeter type of relay with a reg" ulating device gives a sensitive operation of that regulating device insofar as time delay is com cerned without a large number of unnecessary,

operations.

In practice, it is of course desirable that the voltmeter type of relay employed as the control apparatus of the regulator, be not susceptible to changes in. temperature particularly in outdoor installations where the. ambient temperature varies over a wide range. Further, line drop compensation must also be employed in order to obtain correct operation of the regulator.

use of the lmown line drop compensators involves a variable resistance and a reactarice connected in series with the primary winding of the voltmeter whereby the voltage drop across the compensator is proportional to the line drop and is subtracted from the voltage which is prooortionel to the voltage which is to be regulated to give a resultant voltage across the primary winding of the voltmeter which simulates the voltage at the load center. Such compensate-rs introduce additional complications in the regulating system.

It is an object of this invention to provide a regulating system which is substantially unaffected by changes in ambient temperature and {till of this invention is to provide a voltmeter type of relay which is substantially imaliected by changes in ambient temperature and which is provided with a self-contained line compensator and inherent inverse time olelay;

Gther objects of this invention will become ap-= parent from the following description, when talreh. in conjunction with the accompanying drawing, in which:

Figure l is a diagrammatic view of the apparates c cults comprising one embodiment of this inveiflulo is a graph curves of which illustrate the correction factor for the relay of this invention when employed. with electric circuits having dlf ferent power factors;

S is a diagrammatic view or a modification of a. part of the apparatus and circuits illustretecl in Fig. l; and

Fig. i is a. simplified vector diagram of a relay of the type utilised in this invention.

Referring to Fig. l of the drawing, 8. tap changing regulator it is provided for regulating the voltage of the circuit comprising conductors i and it, The regulator it comprises the primary winding is connected across a source of alternating current power designated by 'conductors it and and the secondary winding IS, the different sections of which are disposed tobe connected across the conductors ii and i2 representative of the feeder or load circuit.

The motor in? is provided for adjusting the electrical connection to the taps of the secondary winding i l to control the voltage across con doctors ill and 32, When energized from a suitehle source of power such its the battery il by the actuation of a control contactor ill, the Inctor operates the regulator it in the circuit volt age raising direction. When energized by the actuation of a control contactor it, the motor it operates the regulator ill in the opposite or circuit voltage lowering direction.

A primary relay is utilized to selectively control the energizetlon of the contectcrs it ill. The relay 2%? is disposed to be energized through the potential transformer 2| in accordance with predetermined changes in the voltage across conductors it and. i2 and its operation is afiected by the line drop as measured through the current transformer 22.

The relay 29, shown as being of the induction type, comprises 8. maguctizable core structure having an outer ring 23, an upwardly projecting central leg 24 and two downwardly extending spaced legs 25 and 28. windings 21 and 28 are carried on the leg 24, the winding 28 being connected in series circuit relation with the series connected windings 29 and 30 carried on the legs 25 and 26, respectively. Auxiliary compensating windings 3i and 32 are also carried on the legs 25 and 26, respectively, and are connected in series circuit relation with each other.

As illustrated, a movable disk 33 of copper or other suitable material is rotatably mounted between the ends of the pole pieces or projecting legs of the magnetic circuit disposed to be moved in one or the other direction, dependent upon the energization of the windings oi. the relay. When the disk 33 is moved, a contact member 34 carried thereby is actuated to engage one or the other of stationary contact members 35 or 36 to energize the windings or. one or the otherof the contactors l8 or l9, depending upon the direction of movement of the contact member 34. The winding of the contactor l8 or [9 is connected across the power source represented by conductors 31 and 38 when the contact member 34 engages the stationary contact members 35 or 36, respectively, associated therewith.

The contact members 35 and 36 are adjustably mounted in order to set the relay for the voltage regulation band width required. As in usual practice a spring (not shown) is secured to the shaft of the disk 33 for determining the scale calibration of the relay 20. When the windings of the relay are deenergized, the contact member 34 is normally held in engagement with contact member 35. The strength of the spring (not shown) determines the spread of the calibration for, as is well known, if the spring tension is too strong the contact member 34 will not move except in response to very high voltage across conductors H and I 2. As illustrated, a permanent magnet assembly 9 is provided for imparting time delay in the operation of the relay 20, the eiIect of the permanent magnet varying inversely as the change in the voltage so as to give a sensitive inverse time delay in the operation of the relay.

The windings 29 and 33 on the legs 25 and 26 respectively are so carefully constructed that the reactance of the circuit of these legs or poles equals their resistance to give the windings a 45 impedance angle. This is done in order to make any temperature error due to the upper legs or pole impedance a minimum, it being readily established that such temperature error is a minimum under such conditions.

Even with such adjustment of the windings 29 and 30, it is found that a change in ambient temperature also produces such variations in the relay impedance that the current in the potential circuit of the relay varies with the temperature even though the voltage remains constant. For this reason, a swamplng or ballast reactor 39 is connected in series with the potential winding 21 and the transformer 2i. The impedance of the reactor 39 is so large that about 80% of the voltage across the conductors H and i2 is used across the reactor 39. Thus the current in the winding 21 is to a large extent independent of the impedance of the relay, such impedance being small with respect to the total potential circuit impedance. With the reactor 35 connected in the circuit as described, it is found that variations in relay impedance have substantially no effect on the total impedance of the voltage circuit and the current in the relay remains substantially constant indepenil" ent of temperature changes over a wide range. In the relay illustrated, line drop COKHPQIKSEM tion is applied through th auxiliary windings 3i and 32 carried by the upper poles 25 and 26, respectively. These windings when energized in conjunction with the energization of winding ll are disposed to apply a torque to the induction disk 33 which is proportional to the line drop in opposition to the main relay torque developed on the disk 33 when only the primary winding 21 is energized.

In order that the torque developed by the auxiliary windings 3i and 32 be proportional to the line drop, a slide-wire resistor type of potentiometer 40 is so connected between the line current transformer 22 and the auxiliary wind ings 3i and 32 that as the slide 4| is moved, the magnitude of current in the auxiliary windings 3| and 32 varies while the phase angle of the current stays constant. Thus provision is made for obtaining an adjustment in accordance with the absolute magnitude of impedance of the electric circuit II and 12.

In addition to adjusting for the magnitude of impedance of the electric circuit II and i2, provision is made for adjusting for the phase angle of the impedance of the electric circuit. Such adjustment is obtained by the use of the reactor 39 referred to hereinbefore as compensating for temperature error which would other wise be found in the relay. The reactor 33 when properly selected, performs the function of a phase-shifting network as well as giving an effective shift substantially equal to the imped ance angle of the electric circuit H and I2. With the selection of the reactor 39, the phase angle adjustment is fixed and the compensated relay is theoretically adapted for only one circuit. Practically, however, as will be explained more fully hereinafter, it has been found pos sible to employ the compensated relay 20 in a wide range of circuits without excessive error in voltage regulation.

In operation, the regulator i0 is adjusted to maintain a given voltage across conductors H and I2. Under this condition, the contactors i8 and 19 are in their deenergized position and con" tact member 34 is maintained out of engagement with either of the contact members 35 and 36 due to the'fact that a given voltage within the limits of the voltage regulation band width, is applied to the relay.

If for any reason the voltage across conductors H and I2 should increase, the energize tion of the winding 21 is increased and conse quently the windings 28, 29 and 30 inductively coupled therewith are so energized as to apply a torque to the disk 33 and actuate the contact member 34 into engagement with contact member 36. When contact members 34 and 36 are in engagement, a circuit is closed extending from conductor 3! through the contact members 34 and 36, the energizing winding of contactor Hi to the conductor 38 to energize the contactor i9 and actuate its circuit closing member to a circuit closing position. Under this condition,

the motor i6 is energized to actuate the tap changing regulator ID to decrease the voltage across conductors H and 12.

During this operation, the reactor 39 functions to compensate for the phase angle of the elec- At the same time. the

trio circuit H and I2.

windings 3| and 32 are energized through the resistor 40 from the current transformer 22. The energization of the auxiliary or compensating windings 3| or 32 produces a torque on the disk 33 in opposition to the torque produced by the increase in the energization of the winding 21 and the windings 28, 29 and 30 inductively coupled therewith and is proportional to the current in theelectric circuit I l and i2. The amount of compensating or auxiliary winding torque is also dependent upon the phase angle between the line current and the line voltage. Thus with the torque affecting the actuation of the disk 33 dependent upon both the voltage across conductors II and I2 and the load current of the electric circuit, it is readily seen that the operation of the relay 20 is such as to correct for the conditions at the load center, the reactor 39 correcting for the phase angle of the impedance of electric circuit and the resistor 40 correcting for the magnitude of that impedance.

With this compensation, the disk 33 is actuated to control the operation of the regulator ID to maintain the required vo tage at the load center.

During the operation it is found that changes in the ambient temperature do not substantially affect the operation of the relay 20. This is because of the selection of the windings 29 and 30 referred to hereinbefore and the inclusion of the swamping reactor 39 in the potential circuit. The effect of the windings 29 and 30 and the reasons for so selecting them that the reactance of the circuit of the legs or poles 25 and 26 equals their resistance will be better understood by reference to Fig. 4 in which a simplified vector diagram of an induction relay is illustrated.

In the vector diagram i1 is the current flowing in the primary winding 27 and in is the flux produced thereby. The secondary voltage e2 across the winding 28 is illustrated as 90 behind the primary current ii, with the secondary current in flowing in the secondary circuit including windings 29 and 30 lagging the secondary voltage e: by an angle b which -is a function of the resistance R2 and reactance-Xz of the secondary circuit, the flux of which is designated as $2. Considering that the torque of the disk may be represented by the equation T=KM sin a (1) then for maximum torque, a should equal 90. However a=90-b and since then a-90(t8.n

If the relay secondary windings are designed for maximum torque, that is, a=90, then when R: changes due to a change in the ambient temperature, the Equation 2 shows there is no eflfect on the angle a although the secondary current in changes in magnitude due to the change in the resistance R2. Therefore, the flux In which equals kiz, also changes in magnitude and from Equation 1 it is seen that the torque must vary. In other words, with the windings designed for 11:90 there is a variation of relay torque with a change in ambient temperature resulting in an GllOl'.

However, if the secondary windings 29 and 30 are so selected that the angle a is approxi mately 45, a variation in R2 also changes the value of angle a (see Equation 2) which tends is fixed, the relay 2t? embodying such rt 'so selected that it will perform the it ction o vtlon of the load power factor w to compensate for any change in triage the flux In. Thus if the temperatur the resistance R: increases and the creases, the normal tendency oi. wi? duce the torque, However, when ti R2 increases, the angle it also increa. s to increase the torque, as indicated try 1. The net result of such changes is change in the angle a neutralizes the on. magnitude of the flux stand the torque constant, independent of a wide variation temperature.

From the above, it is evident that the functions as an ammeter, that is, its com is dependent on the flow of current and m" rectly on the voltage across its termina inclusion of the swamping reactor in i: tentiai circuit in series with the wind sures such functioning of the relay, to. ance of the reactor 39 being so large Chat, th impedance of the relay is quite small with. T2. spect to the total primary circuit impedance the current flowing in the circuit 'soroi'oie, substantially independent of the impedance the winding 21.

If for any reason the load current incre ses, the resultant or net torque on the dish. creases even though the voltage across ductors ii and it remains unchanged.

where the movable contact member the contact member to to close a oi. ergize the Winding of contactor W.

phase shifting network giving an eiiec e hift its be employed with different circuits. pie, if the reactor is designed so that r in series with the winding of the 1 angle between the iropi'esseiri vo voltage across the relay is til", then th be employed with any 46 electric the relay can be operated correctly for and any power factor providing the slit, of the load drop compensator is set true magnitude of full load line drop.

If this 40 corrected relay is empioye junction with an electric circuit whos ance angle is 70 instead of the. no longer gives correct voltage indies compensating resistor is adjusted i magnitude of iull load line drop. any given power factor. a seti" s drop compensator can be found wi the relay 2!! operate correctly for any i particular power factor. load drop compensator can be r by a compensator correction factor w ich eilect, an intentional error in the compensator ll; to correct for the error i. relay phase angle setting.

Referring to Fig. 2 of the drawing, shown a set of curves which. illust compensator correction factor var.

is used on diiierent lines. These on a 40 relay since so has hecn an impedance angle of 60 where the power fac-- torvaries from 80 to 90%, by referring to Fig 2, it issseen that the correction factor for 80% power factor'is .91 and the correction factor for 90% power factor'is .85. The-average correction factor is then .88 and the variation plus minus .03. Thus if the true line drop at full load is volts in terms of the transformer, 2|, secondary circuit, the slide wire 4| of the compensator 40 is set at .88 10=8.8 volts. maximum error would then be :.03 X10: 1-.3 volt. As is obvious, the error in such case would be very small, and it will be readily appreciated The that the narrower the range of power factor the smaller would be the relay voltage errors. slight errors can, however, be eliminated by providing for the adjustment of the reactor 39 or by providing an adjustable phase shifter in place of the reactor 39.

Referring to Fig. 3, there is illustrated an adjustable phase shifter to be employed in place of the fixed reactor 39 of the embodiment illustrated in Fig. 1. In this embodiment, a fixed resistor 42 is disposed to be connected in series with a part of the reactor 39 and with the winding 21 when the circuit closing member 43 is actuated to its circuit closing position. A phase shifter of this type is satisfactory for use with the relay where the relay is to be employed with electric circuits having an impedance angle of between 5 and As illustrated, the reactor 39 is also disposed to be connected in circuit with the winding 21 by the circuit closing member 44 so that the fixed reactor is employed as the phase shifting member in the same manner illustrated in Fig. 1, such phase shifting member being completely satisfactory for use with electric circuits having an impedance angle of between 30 and Where the electric circuit with which the relay is to be employed has an impedance angle of between 50 and 70. then the combination of the reactor 39, the capacitor 45 and resistor 46 may be employed as the phase shifting network. In this embodiment, the capacitor 45 and resistor 46 are connected in series circuit relation with each other and are disposed to be connected in parallel relation with the reactor 39 when the circuit closing member 41 is actuated to its circuit closing position and the combination of the reactor 39, capacitor 45 and resistor 46 are connected to the winding 2! by the circuit closing member 44. By using similar phase shifting networks, suitably modified, the phase shift angle may be controlled to as fine a degree as may be required.

With the embodiment illustrated in Fig. 3, an adjustable phase shifter is provided which, in addition to compensating for the phase angle of the impedance of the electric circuit, also compensates for any temperature changes whereby the current in the winding 21 of the relay is substantially unaffected by any change in ambient temperature.

Such

In the interest of maintaining the description of this invention clear and definite as to the apparatus and circuits employed, the description has not been complicated by the inclusion of the mathematical derivation of formulae for determining the required impedan e of the ballast reactor, impedance of the windings of the relay, line drop compensating resistor or the correction factor referred to hereinbefore. Details of the design of the relay and the derivation of the formulae can be had by reference to the paper entitled A New Voltage Regulating Relay Plus Line Drop Compensation by H. J. Carlin which was presented at the January 1942 A. I. E. E. convention.

The regulator control equipment described hereinbefore can be employed satisfactorily with any type of regulator being provided with its own inherent line drop compensation and is substantially unaffected by changes in temperature. When employed in conjunction with a tapchanging transformer regulator, the regulating equipment of this invention makes such tapchanging transformer approach the effectiveness of an induction regulator. Further, the control equipment is simplified since it is only necessary to provide one adjustment for line drop compensation without introducing excessive errors in voltage when used in conjunction with regulating equipment on low capacity lines.

Although this invention has been described with reference to a particular embodiment thereof, it is, of course, not to be limited thereto except insofar as is necessitated by the appended claims.

I claim:

1. In combination, an electric circuit having a line impedance, regulator means connected to said circuit for varying an electric quantity thereof, a primary relay for controlling the regulator means, the relay comprising a magnetic core structure, a plurality of windings disposed thereon, and a disk disposed for movement when the windings are energized to produce a. torque thereon for controlling the regulator means. one of the windings being supplied with electric energy at a voltage that is a measure of the voltage of the electric circuit, compensating means connected in circuit with said one of the windings for compensating for the phase angle of the impedance of the electric circuit, said compensating meansmaintaining the current in said one of the windings substantially constant for changes in ambient temperature, another of the windings being supplied with electric energy at a current value that is a measure of the current in the electric circuit, and compensating means connected in circuit with said another of the windings, for compensating for the magnitude of the impedance of the electric circuit independently of the phase angle of said impedance.

2. In combination, an electric circuit having a line impedance, regulator means connected to said circuit for varying an electric quantity thereof, a primary relay for controlling the regulator means, the relay comprising a magnetic core structure, a plurality of windings disposed thereon, and a disk disposed for movement when the windings are energized to produce a torque thereon for controlling the regulator means, one of the windings being supplied with electric energy at a voltage that is a measure of the voltage of the electric circuit, a reactor connected in circuit with said one of the windings for compensating for the phase angle of the impedance of the electric circuit, said reactor having an impedance large with respect to the impedance of said winding whereby the current in said winding is substantially constant for changes in ambient temperature, another of the windings being supplied With electric energy at a current value that is a measure of the current in the electric circuit, and compensating means connected in circuit with said another of the windings for compensating for the magnitude ofthe impedance of the electric circuit independently of the phase angle of said line impedance.

3. In combination, an electric circuit having a line impedance, regulator means connected to said circuit for varying an electric quantity thereof, a primary relay for controlling the regulator means, the relay comprising a magnetic core structure, a plurality of windings disposed thereon, and a disk disposed for movement when the windings are energized to produce a torque thereon for controlling the regulator means, one of the windings being supplied with electric energy at a voltage that is a measure of the voltage of the electric circuit, compensating means connected in circuit with said one of the windings for compensating for the phase angle of the impedance of the electric circuit, said compensating means maintaining the current in said one of the windings substantially constant for changes in ambient temperature, another of the windings being supplied with electric energy at a current value that is a measure of the current in the electric circuit, a resistor connected in circuit with said another of the windings for compensating for the impedance of the electric circuit independently of the phase angle of said impedance, and means for adjusting the resistor to vary the compensation in accordance with the magnitude of the impedance of the electric circuit.

4. In combination, an electric circuit having a line impedance, regulator means connected to said circuit for varying an electric quantity thereof, a primary relay for controlling the regulator means, the relay comprising a magnetic core structure, a plurality of windings disposed thereon, and a disk disposed for movement when the windings are energized to produce a torque thereon for controlling the regulator means, one of the windings being supplied with electric energy at a voltage that is a measure of the voltage of the electric circuit, a reactor connected in circuit with said one of the windings for compensating for the phase angle of the impedance of the electric circuit, said reactor having an impedance large with respect to the impedance of said winding whereby the current in said winding is substantially constant for changes in ambient temperature, another of the windings being supplied with electric energy at a current value that is a measure of the current in the electric circuit, a resistor connected in circuit with said another of the windings for compensating for the impedance of the electric circuit independently of the phase angle of said impedance, and means for adjusting the resistor to vary the compensation in accordance with the magnitude of the impedance of the electric circuit.

5. In a regulating system, an electric circuit having a line impedance, regulator means connected to said circuit for varying an electric quantity thereof, a primary relay for controlling the regulator means, the relay comprising amagnetic core structure, a plurality of windings disposed thereon, and a disk disposed for movement when the windings are energized to produce a torque thereon for controlling the regulator means, one of the windings being connected across the electric'circuit and responsive to the voltage thereof to produce a torque on the disk,

- a reactor connected in series circuit relation with said one of the windings for maintaining the current in the winding substantially constant for changes in ambient temperature, the reactor also compensating for the phase angle of the impedance of the electric circuit, another of the windings being connected to the electric circuit and responsive to the current thereof to produce a torque on the disk in opposition to the torque produced by said one of the windings, and a resistor connected in circuit with said another winding to control the energizing current therein independently of the phase angle of the impedance of the electric circuit, said resistor being adjustable for compensating for variations in the magnitude of the impedance of the electric circuit, the windings thereby cooperating to produce a resultant torque on the disk which is compensated for the impedance and the phase angle of the impedance of the electric circuit to control the regulator means to vary an electric quantity of the electric circuit.

HERBERT J. CARLIN.

RUTH M. CRICHTON. Administratrix of the estate of Leslie N. Crichton,

deceased. 

